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<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>
  <script>
    //声明一个set
  let s = new Set()
  let s2 = new Set(['好事','坏事','大事'])

  console.log(s, typeof s)
  console.log(s2.size)
  s2.add('小事')
  s2.delete('坏事')
  s2.has('xioashi')
  // s2.clear()
  // console.log(s2)

  for(let v of s2){
    console.log(v)
  }
  </script>
  
</body>
</html>